Photographic materials and method of producing the same



United States Patent PHOTOGRAPHIC MATERIALS AND METHOD or PRODUCING THESAME Millet R. De Angelus and Fritz Dersch, Binghamton,

N.Y., assiguors to General Aniline & Film Corporation, New York, N.Y., acorporation of Delaware No Drawing. V Filed Mar. 3, 1959, Ser. No.796,756

" '11 Claims. (Cl. 9 6-6 6 The present invention relates to antifoggingand stabilizing agents for photographic silver halide emulsions and,more particularly, to light-sensitive silver halide materials containingas a stabilizing and antifogging agent a tn'azine each carbon atom ofwhich is substituted by a heterocyclic thioether group. a

It is well known in the photographic art that lightsensitive emulsions,such as gelatino silver halide emulr 2,948,612 Patented Aug. .9, 1960amount ranging from 1 milligram to 2 5,milligrams per 0.6 mol of silverhalide and when used as a coating final they are preferably added in anamount ranging from 10 milligrams to 300 milligrams per 0.6 mol ofsilver halide. The optimum amountto be added depends primarily on thetype of emulsion and should be determined individually in each case.

sions, have a tendency to fog. Fog is usually caused by 4 a prolongedripening of the emulsions, by prolonged storage especially at elevatedtemperatures and humidity, and by prolonged development. To overcomethis undesirable-property, it has been the practice in this art to addcertain chemical compounds to the emulsions to increase theirstabilityand to reduce their tendency to fog. However, all stabilizing andantifogging compounds heretofore used in this art have the disadvantagethat upon addi-,

tion to the emulsion thy cause a loss of speed and/or contrast of theemulsion.

It is, accordingly, an object of this invention to produce alight-sensitive emulsion which is fast, stable, has a reduced tendencyto fog and has good contrast.

A further object of this invention resides in a'light-' sensitiveemulsion which contains a compound which stabilizes the emulsion againstfogging and at the same time does not materially reduce the speed and/orcontrast of the emulsion. I

A still further object of invention is to provide a light-sensitiveemulsion containing a compound which stabilizes the emulsion againstfoggingand at the same time does not appreciably reduce the sensitivityto light of longer wave length efiectd by the presence of sensitizingdyes.

Other objects andvadvantages of this invention will ap' pear to thoseskilled in the art from the detailed description,t-l1ereof given below.

i 'Ihestabilizers and antifoggants contemplated for use herein may betypified by the following structural formula:

-3. in w hich R, is thiazolyl, ,imidazolyl, oxazolyl, benzothja'zolyl,benzimidazolyl or benzoxazolyl.

The antifogging agents of our invention may be added qthe. ennrlsion atany stage during its process of production.- Thus, they may be added asa ripening final or as a. coating final? When added as a ripening final,

The stabilizers and antifoggants of our invention may also be used incombination with known antifoggants and stabilizers. The antifoggants ofour invntion can also be used in combination with sensitizers such assulfur, metal and reduction sensitizers as well as with acceleratorssuch as the polyoxyethylenes (see U.S.P. 1,970,578) and their,

derivatives and polyvinyl-pyrrolidone.

The novl antifoggants of our invention may be used with various types ofphotographic emulsions, such as;

non-sensitized, orthochromatic, panchromatic and X-ray emulsions, paperemulsions and color emulsions.

The antifoggants and stabilizers of the present invention'are preparedbythe dropwise addition to an organic solvent solution of cyanuricchloride of a Z-mercaptobenzothiazole, -benzimidazole,' -benzoxazole,-thiazole,

-imidazole or -oxazole while the latter is dissolved in an aqueous lowboiling organicsolvent such as acetone, butyl acetate or thelike in thepresence of an acid binding agent 9 such as potassium hydroxide, sodiumhydroxide, sodium The following examples illustrate a method of prepargiodide and'98% silver bromide was prepared in a concarbonate or thelike. After commingling the reactants,

the mixture is stirred at a temperature of from 5.0 C.

and. then chilled and filtered. The resulting solid may be.

purified by washing with. acetone and recrystallized from benzene. V

ing'one of the compounds falling under the general formula given aboveand the manner of using the compound in conjunction with light-sensitivephotographic silver halide emulsion. his to be understood, however, thatthese examples are given by way of illustration only and not by way oflimitation.

Example I A silver halide emulsion in gelatin containing 2% silverventional rnanner and brought up to-its maxim-um light sensitivity. Itwas then readied for coating, finals were added such as sensitizing dyesand harden'ing agents. A 1% solution of 2,4,6-tni(benzothiazolyl-2-thio)-S-tri- -azine was prepared and added in varyingamounts to samples of the emulsion as an antifoggant and stabilizer."

Each emulsion sample contained'about 0.6 mol of silver halide. Theso-prepared emulsion samples were coated on a suitable cellulose esterbase and dried. Samples of these film coatings were then-exposed in aType 'IIB Sensitometer, and developed in a developerofthe followingcomposition:

Grams I The results obtained were as follows:

Oven Fog .at; 6 Development Relative The compound 2,4,6-tri(benzothiazolyl-Z-thio) -S- triazme used above has the followingchemical structure:

The method used by us in preparing this compound is as follows:

To a stirred solution containing 8.4 grams of (.05 mol)Z-mercaptobenzothiazole, 150 ml. of acetone, 8 ml. of H 0, and 3.3 gramsof potassium hydroxide (.05 mol) was added dropwise a solutioncontaining 3.1 gram (.017 mol) of cyanuric chloride in 100 ml. ofacetone. The addition was carried out at room temperature. The stirredreaction mixture was heated to 60 C. for hours, and then chilled andfiltered. The solid was washed with 20 ml. of acetone, then with wateruntil free of the inorganic salts. After crystallization from benzene,the pale yellow product melted at 210-211" C. (uncorrected). Yield-5grams. Calcd. for C H N S N: calcd., 14.58%; found, 14.53% S: calcd.,33.33%; found, 33.14%

Example 11 Exposed samples of a photographic film were developed fortwelve minutes at 65 F. in a standard p-(N-methylamino)phenolhydroquinone developer. Two tests were made, one with the normaldeveloping solution and one with a developer containing 100 mgs. of2,4,6-tri (benzothiazolyl-2-thio)-S-t1iazine per one liter of developer.Sensitometric strips, developed in the normal developer (control) fortwelve minutes showed a fog of .30, whereas those strips, which weredeveloped in the developer containing the antifoggant had a fog of .20.

Example III The procedure is the same as in Example I excepting that theantifoggant and stabilizer is 2,4,6-tri (benzoxazolyl-Z-thio)-S-triazine. The results obtained with this compound are similar tothose of Example I.

This compound is prepared by the same method as that used in Example Iexcepting that the 2-mercaptobenzothiazole is replaced by .05 mol ofZ-mercaptobenzoxazole.

Example IV The procedure is the same as in Example II excepting that theantifoggant and stabilizer employed is 2,4,6-tri (imidazolyl-Z-thio)-S-triazine or 2,4,6-tri (thiazolyl-Z- thio)-S-tn'azine.

These compounds are prepared in the same manner as the compound ofExample I, excepting that 2-mercaptoirnidazole or 2-mercapto-thiazole isused in lieu of the 2- mercapto-benzothiazole.

Modifications of the invention will occur to persons skilled in the art.We, therefore, do not intend to be limited in the patent granted exceptas necessitated by the appended claims.

4 We claim: 1. A light-sensitive material comprising a base and alight-sensitive silver halide emulsion thereon, said material containingan antifoggant and stabilizing compound having the following chemicalformula:

wherein R is selected from the group consisting of thiazolyl,imidazolyl, oxazolyl, benzothiazolyl, benzimidazolyl and benzoxazolyl.

2. A light-sensitive silver halide emulsion containing 2,4,6tri(benzothiazolyl-2thio)-S-triazine as an antifogw gant and stabilizer.

3. A light-sensitive silver halide material as recited in claim 1wherein the antifoggant and stabilizing compound is present in theemulsion and in the ratio of 1 to 300 milligrams per 0.6 mol of silverhalide.

' 4. A light-sensitive silver halide emulsion as recited in claim 2wherein the antifoggant and stabilizing compound is present in theemulsion in the ratio of 1 to 25 milligrams per 0.6 mol of silverhalide.

5. A light-sensitive silver halide material as recited in claim 1wherein the antifoggant and stabilizing compound is present in theemulsion and in the ratio of 10 to 300 milligrams per 0.6 mol of silverhalide.

6. A light-sensitive photographic element as recited in claim 1 whereinthe antifoggant and stabilizing compound is 2,4,6-tri(benzothiazolyl-Z-thio)-S-triazine.

7. In a process of developing an exposed silver halide emulsion, thestep which comprises developing said emulsion with ap-(N-methylamino)phenol-hydroquinone developing solution in the presenceof an antifogging and stabilizing compound having the following chemicalformula:

ing solution containing a compound'having the following wherein R isselected from the group consisting ofthiazolyl, imidazolyl, oxazolyl,benzothiazolyl, benzoimidazolyl and benzoxazolyl.

10. A p (N-methylamino)phenol-hydroquinone de veloping solutioncontaining 2,4,6-tri (benzothiazolykZ- thio) -S-triazine.

11. A p-(N-methylamino) phenol-hydroquinone developing solutioncontaining milligrams of 2 ;46 tfi' (benzothiazolyl-Z-thio) S-triazineper liter of solution.

References Cited in the file of this patent UNITED STATES PATENTS2,476,536 Dersch Ju y 1 .19

1. A LIGHT-SENSTITIVE MATERIAL COMPRISING A BASE AND A LIGHT-SENSTITIVESILVER HALIDE EMULSION THEREON, SAID MATERIAL CONTAINING ANTIFOGGANT ANDSTABILIZING COMPOUND HAVING THE FOLLOWING CHEMICAL FORMULA: